The present invention pertains to a clamping element for clamping workpieces in a flexible position with hydraulically actuated clamping jaws, which can be moved to the workpiece and fixed and make the clamping element into a floating element.
Clamping elements are used to clamp workpieces in order to fix the workpiece immovably against all forces occurring during machining. It is necessary here to mount the workpiece in a positioned manner and to clamp it in this position and, furthermore, to support it with clamping elements wherever twisting or deformations of the workpiece may occur as a consequence of the forces occurring during machining. These clamping elements, which are preferably used to support the clamping operation, must have such a design that when brought into contact with the workpiece, they do not generate any transverse forces, which affect the preset position of the workpiece.
These clamping elements are usually brought to the workpiece in a hydraulically actuated manner. This approaching movement leads to a compensation between the clamping jaws located opposite each other to ensure that these come into contact with the workpiece with equal force. To achieve this, the hydraulic fluid is supplied to the drive mechanisms and the clamping jaws uniformly via only one delivery line, so that the distribution of the forces between the clamping jaws takes place via the hydraulic fluid. The clamping jaw that is the first to touch the workpiece stops as a consequence of the resistance originating from the workpiece, while the other clamping jaw continues to move until it comes into contact with the workpiece. A pressure acting uniformly on the workpiece is now building up between the two clamping jaws. However, if forces that are greater than the holding forces generated by the hydraulic system alone act on the workpiece, deformation of the workpiece will take place and the machining process will be compromised.
The prior-art clamping elements are subject to considerable frictional forces because of their design. This is due in part to seals which are necessary in the hydraulic system and seal the cylindrical parts against one another, while these are moving together. Large dimensions lead to heavy weights of the moving parts and consequently also to inertia forces, as a result of which deformations on the workpiece will not fail to occur, which leads to inaccuracies in production. Moreover, the clamping range of such elements cannot be adapted to all applications, which causes elements of different sizes to become necessary for machining different workpieces.
Thus, the object of the present invention is to associate with the clamping element a large clamping range, which can be adapted to different workpieces and to introduce the forces into the clamping operation such that they bring about the fixing of the workpiece without affecting same in its positioned position, and to maintain the holding forces introduced into the workpiece during the machining operation regardless of external effects.
According to the invention, a clamping element is provided for clamping workpieces in a flexible position with hydraulically actuated clamping jaws. The clamping jaws may be moved to the workpiece and can be fixed. A clamping insert with an internally located piston is guided slidingly in a housing. The clamping insert is provided with a clamping jaw and accommodates a clamping lever via a turning knuckle. The clamping lever is connected to the piston via a connecting rod in an articulated manner. The piston presses the clamping lever onto the workpiece during the clamping operation and raises the clamping insert due to the resistance exerted by the workpiece on the clamping lever, thus moving the clamping jaw under the workpiece. The workpiece becomes firmly connected to the clamping insert due to the build-up of force between the clamping lever and the clamping jaw.
The housing may have a cutout on one side. The clamping insert may be slidingly guided in the cutout via bevels provided in the housing and via guide surfaces provided on the clamping insert. The clamping insert may be provided on its side located in the cutout with a plurality of positioning holes, in which the clamping jaws can be accommodated in a positioned manner. The clamping jaw may be equipped with a fine adjusting screw.
A clamping piston may be guided in the housing in a cylindrical hole at right angles to the clamping insert. The clamping piston may move toward the clamping insert when pressure is admitted and presses same with its guide surfaces into the bevels of the housing and fix same.
The feed lines of the hydraulic system to the connections in the clamping insert may be flexible.
A spring may be supported at the bottom of the housing. The spring force of this spring may compensate the weight of the clamping inserts. The spring may be inserted into the clamping insert.
The clamping insert may have a cylindrical design and may be slidingly guided in a housing. A piston may be provided with a connecting rod and with a clamping lever at the head and may be mounted in the clamping insert. The clamping piston has a pressing surface that may have a prismatic design and may be adapted to the cross section of the clamping insert. This may press the clamping insert into the wall of the cylindrical hole in the housing when pressure is admitted. The pressing surface may be arranged at right angles to the clamping insert.
The tubular springs may establish a flexible connection for the hydraulic system between the outer connections on the housing and the pressure chambers in the cylindrical space of the clamping insert for the actuation of the piston. These tubular springs may be arranged in the housing below the guided clamping insert. The tube springs may be connected to the ends with the corresponding connections and channels by means of nipples and straps.
The various features of novelty which characterize the invention are pointed out with particularity in the claims annexed to and forming a part of this disclosure. For a better understanding of the invention, its operating advantages and specific objects attained by its uses, reference is made to the accompanying drawings and descriptive matter in which preferred embodiments of the invention are illustrated.